I know the L03 305 engines had a small bore diameter than the 350's did by about .4". A 350 block will have a 4" bore and a 305 L03 will have a 3.6" bore, approximately. But other than that are the parts put in or on the block interchangeable? E.G: Heads, intake manifold, cam, etc. I was interested in maybe upgrading my 305 little by little to learn about the engine and how everything is put together. Don't get me wrong I'm very familiar with how engines work, but knowing how they work and working on them are two different beasts. Eventually I would like to get a 350 block to build and put in, so I wasn't sure if I should waste money on upgrading the 305 and then transferring it's upgrades to the 350 when I get the block; or just start from scratch with a 350 and not bother with tinkering with the 305. I have read many forums about how spending money on a 305 is a waste because you get 5x the output with a 350 for the same amount of money. I do plan on putting a 350 in it, so that is not the issue. Right now I just want a little more kick out of the 305 before I drop a 350 in it, and if i can buy parts for it that can eventually be put on the 350, that would be great. I have to keep the car running since it gets me to and from work. lol. Thanks guys.

 

That's one of the great things about the small block chevy.. It's very interchangeable.

If a part bolts to one, it will bolt to all.. With only a few exceptions to that due to minor changes made over the years.

You can swap heads, intake, headers, cams, etc from a 305 to 350 to 267, etc.

Know the changes and you will know what will work and what will need modding and what just will not work.

Here is something I typed up years ago and saved to me computer

1955 1st chevy small block 265 cid, only front engine mounts
1956 Oil filter mounting pad added
1957 283 introduced, 283 HP with mech. FI, removed rear grooved cam bearing from block
1958 Side engine mounts added
1959 Rope seal replaced by 2 pc rubber rear main seal
1960 1st factory alum. Heads introduced (recalled because of porosity probs)
1961 283 makes 315 HP with mech. FI
1962 327 introduced
1964 1st 2.02”/1.60” valve heads, 327 fuelie makes 375 HP
1965 Last year for mech. FI
1966 327/350 HP engine introduced with hyd. Cam
1967 Last year for 283, 1st year for 302 and 350. 350 introduces larger journal sizes
1968 All small blocks go to larger journals, temp sender from intake to head
1969 Last year for 302, 1st year for long water pump, all heads gets acc. Mounting holes
1970 400 sb introduced, LT1 350 makes 370 HP in corvette
1971 Compression ratio drops due to emission regs.
1972 Last year for solid cams and holley carbs in hi-po engines
1974 HEI ignition introduced
1976 305 introduced
1979 Oil dipstick moves from driver to pass side
1980 Last year for 400, 1st year for computer controlled system
1981 Crossfire injection introduced
1985 Tuned port injection introduced
1986 Major changes.. Center bolt valve covers, new oil pan flange, 1 pc rear seal. 3.58” dia. Flywheel flange changed to 3.00”
1987 Intake center bolt angle changed from 90* to 73*.. L98 alum vette heads keeps 90*, hyd roller cam provisions added
1992 Gen II engine introduced.. LT1 350
1996 Vortec truck engine introduced with high flow heads, roller cam, plastic timing cover, 8 intake bolts.. Gen II LT4 hits 330 HP with roller rockers, high flow alum heads
1997 LS1 installed in corvette
1998 LS1 installed in F body


Heads…
1969 and up got acc. Mounting holes
1955-59 have staggered valve cover mount pattern
Temp sender moved to head in 1967
Starting in 1970 all 2.02/1.60 heads got screw in rocker studs

Flywheel, flexplate, starter, damper
153 tooth 12.75” od
168 tooth 14” od
1955-68 dampers have timing marks 2* before keyway center line
1969 and up dampers have timing marks 10* before keyway centerline


1955-67 engines uses rods with 11/32: rod bolts, 68 and up has 3/8” rod bolts

 

Thanks man! That's exactly what I needed! Now if only there was a shop around where I live that did performance tunes on the stupid ECM.

 

I'd stick with doing your rear gears (3.42s or 3.73s) & exhaust. The only thing I'd do to the 305 itself is bump up the timing.

 

the ol 265!! You know what name that motor got dont ya?? Mighty mouse! lol.

 

Id go with 3.42 or even 3.23 gears. 3.73s will trip your speed limiter off at around 88mph unless you change vss gears or get chip burnedto eliminate the speed limiter if you stay with your TBI. Gears, posi, custom tune, and good exhaust will wake up the lil L03 a lot.

 

Every one always says to get the ECM performance tuned on the L03, but that technology is a dying breed, and it is dying very quickly. I had to call a bunch of different shops to find someone that will tune the ECM, and only one will do it, and they don't really like to. I think that the engine would be better off switched to carb.

 

EBL Flash is the way to go for tbi

 

how exactly do you bump up the timing on a 305TBI in a 1991 Camaro RS?